Video security downloading and playing method based on GB35114 protocol

Abstract

The invention discloses a video secure downloading and playing method based on a GB35114 protocol, and the downloading method comprises the steps: initiating a video downloading request to a video monitoring platform with a GB35114 function, receiving an encrypted SVAC video code stream after the request succeeds, and decrypting the encrypted SVAC video code stream into a plaintext SVAC video code stream; a file SN.lic with the serial number of the security chip as the name is obtained from the security chip, and a UUID and a newVKEK are generated for a video file to be downloaded; the method comprises the following steps: receiving playing information input by a user through a client, writing a UUID, a newVKEK and the playing information into an SN.lic file, generating a new video key newVEK for a received video code stream by taking a GOP as a unit, re-encrypting the code stream through the newVEK to enable the video keys in each key frame interval to be different, encrypting the newVEK into a ciphertext e (newVEK) by using the newVKEK, and sending the ciphertext e (newVEK) to the client. And writing the encrypted e (newVEK) into a security parameter set of the current GOP, and writing the security parameter set and the UUID into the downloaded video file to be stored together.

Description

Technical Field

[0001] The present invention relates to the field of video monitoring, and in particular to a video security downloading and playing method based on GB35114 protocol. Background Art

[0002] In recent years, the country has attached great importance to domestically produced and controllable products. At present, the video industry mainly adopts foreign standards. Due to the constraints of foreign technology, security issues such as illegal access, illegal modification, and illegal theft of video systems frequently occur, seriously affecting the safety of the people and the country. Therefore, the country promulgated the GB35114 standard to provide construction specifications for public video data security. GB35114 is the country's first technical standard for video network information security. It divides the security level from weak to strong into three levels: A-level identity, signaling authenticity and reliability, B-level integrity, and C-level video confidentiality.

[0003] The GB35114 standard requires that when downloading encrypted videos, the confidentiality and integrity of the downloaded video content must be guaranteed to ensure that only authorized persons can view the video content. At the same time, the viewing time and number of views of the downloaded video must also be authorized. Summary of the invention

[0004] In view of the technical defects and technical drawbacks in the prior art, the embodiment of the present invention provides a video security downloading and playing method based on the GB35114 protocol to overcome the above problems or at least partially solve the above problems. The specific scheme is as follows:

[0005] As a first aspect of the present invention, a video security download method based on the GB35114 protocol is provided, the method comprising:

[0006] Initiate a video download request to the video surveillance platform with GB35114 function through the client, and after the request is successful, receive the encrypted SVAC video stream, and decrypt the encrypted SVAC video stream into a plaintext SVAC video stream;

[0007] Get the file SN.lic named with the serial number of the security chip from the client security chip, generate a unique identifier UUID for the video file to be downloaded, and a new video key encryption key, represented by newVKEK;

[0008] The playback information input by the user is received through the client, and the UUID, newVKEK and the playback information are written into the SN.lic file. For the received video bitstream, a new video key newVEK is generated in units of picture group GOP, and the bitstream is re-encrypted by newVEK so that the video key in each key frame interval is different. At the same time, newVEK is encrypted into ciphertext e(newVEK) by newVKEK, and the encrypted e(newVEK) is written into the security parameter set of the current picture group GOP, and the security parameter set is written together with the UUID to the downloaded video file and saved.

[0009] Furthermore, decrypting the encrypted SVAC video code stream into a plaintext SVAC video code stream specifically includes:

[0010] After the request is successful, the ciphertext video key encryption key E (VKEK) is obtained from the response message of the monitoring platform, the security parameter set in the encrypted SVAC video stream is parsed, the ciphertext video key E (VEK) is obtained, the private key information of SM2 is read from the security chip, and E (VKEK) is decrypted into plaintext VKEK through the SM2 algorithm. The plaintext VKEK is used to decrypt E (VEK) based on the ECB mode of the SM4 algorithm to obtain the plaintext VEK. Finally, the plaintext VEK is used to decrypt the encrypted SVAC video stream based on the OFB mode of the SM4 algorithm to obtain the plaintext SVAC video stream.

[0011] As a second aspect of the present invention, a method for securely downloading and playing videos based on the GB35114 protocol is provided, the method comprising:

[0012] Safe video download:

[0013] Initiate a video download request to the video surveillance platform with GB35114 function through the client, and after the request is successful, receive the encrypted SVAC video stream, and decrypt the encrypted SVAC video stream into a plaintext SVAC video stream;

[0014] Get the file SN.lic named with the serial number of the security chip from the client security chip, generate a unique identifier UUID for the video file to be downloaded, and a new video key encryption key, represented by newVKEK;

[0015] Receive the playback information input by the user through the client, write the UUID, newVKEK and the playback information into the SN.lic file, generate a new video key newVEK for the received video code stream in units of picture groups GOP, re-encrypt the code stream by newVEK so that the video key in each key frame interval is different, and encrypt newVEK into ciphertext e(newVEK) by newVKEK, write the encrypted e(newVEK) into the security parameter set of the current picture group GOP, and save the security parameter set and the UUID together with the downloaded video file;

[0016] Video Safe Playback:

[0017] When the client plays a securely downloaded video file, it first reads the SN.lic file in the security chip, then obtains the UUID and security parameter set from the video file, obtains e(newVEK) from the security parameter set, obtains the playback information corresponding to the video file in the SN.lic file through the UUID, and determines whether there is playback permission based on the playback information. If there is playback permission, the video code stream corresponding to the video file is decrypted through e(newVEK), and the SVAC decoder is called to decode and play.

[0018] Furthermore, the method also includes: determining whether the client is a GB35114 Class C device, and if it is a GB35114 Class C device, performing video security downloading, and when downloading videos on the GB35114 Class C device, prompting the user to enter the SN and PIN of the security chip to connect the security chip, and after successfully connecting to the security chip, initiating a video download request to a video surveillance platform with GB35114 function; otherwise, performing a normal download process, directly requesting video downloading from the video surveillance platform, downloading the plaintext video and saving it.

[0019] Furthermore, the method includes: detecting whether there is an SN.lic file in the security chip, and if not, creating a file SN.lic in the security chip with the serial number of the security chip as the name.

[0020] Furthermore, decrypting the encrypted SVAC video code stream into a plaintext SVAC video code stream specifically includes:

[0021] After the request is successful, the ciphertext video key encryption key E (VKEK) is obtained from the response message of the monitoring platform, the security parameter set in the encrypted SVAC video stream is parsed, the ciphertext video key E (VEK) is obtained, the private key information of SM2 is read from the security chip, and E (VKEK) is decrypted into plaintext VKEK through the SM2 algorithm. The plaintext VKEK is used to decrypt E (VEK) based on the ECB mode of the SM4 algorithm to obtain the plaintext VEK. Finally, the plaintext VEK is used to decrypt the encrypted SVAC video stream based on the OFB mode of the SM4 algorithm to obtain the plaintext SVAC video stream.

[0022] Further, the play information includes the play count playNum, the play start time playBegin and the play end time playEnd; the play information corresponding to the video file is obtained in the SN.lic file through the UUID, and determining whether there is a play permission based on the play information includes: by obtaining the UUID from the video file, searching the corresponding UUID in the SN.lic file, searching the UUID in the SN.lic file, obtaining the corresponding play information, and obtaining the play count playNum, the play start time playBegin and the play end time playEnd allowed for the video file. If playNum is greater than 0, and the play time is between the play start time playBegin and the play end time playEnd, it is determined that there is a play permission, otherwise it is determined that there is no play permission. .

[0023] Furthermore, the method further includes: after the video file is played, updating the play count playNum of the current video file in SN.lic to playNum-1.

[0024] Furthermore, decrypting the video code stream corresponding to the video file through e(newVEK) specifically includes: searching for the corresponding newVKEK from SN.lic based on UUID, decrypting e(newVEK) into newVEK through SM4 algorithm based on newVKEK, and decrypting the video code stream of each frame in the video file through newVEK.

[0025] Further, the method further comprises: when saving the securely downloaded video file, writing a video file header, wherein the video file header comprises characters "SVAC" and a UUID;

[0026] When the client plays a securely downloaded video file, it determines whether the file header of the video file contains the characters "SVAC". If the video file contains the characters "SVAC", the video file is determined to be an encrypted file downloaded securely, and the user is prompted to enter the SN and PIN of the security chip to connect the security chip. After the security chip is connected, the video security playback process is performed; otherwise, the video file is determined to be a non-securely downloaded video file, and the SVAC decoder is directly called for normal playback.

[0027] The present invention has the following beneficial effects:

[0028] The present invention binds the downloaded video file and the security chip of the storage medium, writes the video file playback information into the security chip of the storage medium, and during the storage process, the video file is re-encrypted by transcryption to ensure the security of the downloaded video file. When playing the video file, the playback information of the file is read from the security chip, so that the video file can be played safely. The present invention realizes the safe downloading and safe playback of the video file, and at the same time realizes the authorization of the viewing number and playback time of the downloaded video, etc. There is no specific implementation of the related method in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A flow chart of a video security download method based on the GB35114 protocol provided by an embodiment of the present invention;

[0030] Figure 2 A flow chart of a video security playback method based on the GB35114 protocol provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Embodiment 1:

[0033] This embodiment provides a method for securely downloading and playing videos based on the GB35114 protocol, the method comprising:

[0034] Video safe download, the specific process is as follows:

[0035] A video download request is initiated through the client to a video surveillance platform with GB35114 function. After the request is successful, the ciphertext video key encryption key E (VKEK) is obtained from the response message of the surveillance platform, and the security parameter set in the encrypted SVAC video stream is parsed to obtain the ciphertext video key E (VEK). GB35114 stipulates that E (VKEK) is encrypted by the asymmetric algorithm SM2. Therefore, the private key information of SM2 can be read from the security chip, and E (VKEK) can be decrypted into plaintext VKEK by the SM2 algorithm. E (VEK) is encrypted by the symmetric national secret algorithm SM4, so the plaintext VKEK can be used to decrypt E (VEK) based on the ECB mode of the SM4 algorithm to obtain the plaintext VEK. Finally, the plaintext VEK is used to decrypt the encrypted SVAC video stream based on the OFB mode of the SM4 algorithm to obtain the plaintext SVAC video stream.

[0036] Get the file SN.lic named with the serial number of the security chip from the client security chip, generate a unique identifier UUID for the video file to be downloaded, and a new video key encryption key, represented by newVKEK;

[0037] Receive the playback information input by the user through the client, write the UUID, newVKEK and the playback information into the SN.lic file, generate a new video key newVEK for the received video code stream in units of picture groups GOP, re-encrypt the code stream by newVEK so that the video key in each key frame interval is different, and encrypt newVEK into ciphertext e(newVEK) by newVKEK, write the encrypted e(newVEK) into the security parameter set of the current picture group GOP, and save the security parameter set and the UUID together with the downloaded video file;

[0038] The play information includes the play count playNum, the play start time playBegin and the play end time playEnd;

[0039] Video Safe Playback:

[0040] When playing a securely downloaded video file, the client first reads the SN.lic file in the security chip, then obtains the UUID and security parameter set from the video file, obtains e(newVEK) from the security parameter set, obtains the playback information corresponding to the video file in the SN.lic file through the UUID, and determines whether there is playback permission based on the playback information. If there is playback permission, the video stream corresponding to the video file is decrypted through e(newVEK), and the SVAC decoder is called to decode and play;

[0041] In the above embodiment, after obtaining the playback information, if the number of plays playNum is greater than 0, the video file is read within the start time playBegin and the end time playEnd, and E (newVEK) in the video file security parameter set is parsed, and VEK is decrypted by newVKEK. Then, the video file is decrypted into plain text by VEK, and the SVAC decoding library is called to play. After the video file is played, the number of plays playNum of the current video file in SN.lic is updated to playNum-1.

[0042] The present invention binds the downloaded video file and the security chip of the storage medium, writes the video file playback information into the security chip of the storage medium, and during the storage process, the video file is re-encrypted by transcryption to ensure the security of the downloaded video file. When playing the video file, the playback information of the file is read from the security chip, so that the video file can be played safely. The present invention realizes the safe downloading and safe playback of the video file, and at the same time realizes the authorization of the viewing number and playback time of the downloaded video, etc. There is no specific implementation of the related method in the prior art.

[0043] Embodiment 2:

[0044] See also Figure 1 This embodiment provides a flowchart of video security download based on GB35114 protocol, and the specific steps are as follows:

[0045] Step 101, the client starts a video download request;

[0046] Step 102, determine whether the front-end device is a GB35114 C-level device, if it is a C-level device, proceed to step 104, otherwise proceed to step 103;

[0047] Step 103, normal download process, i.e., non-secure download process, directly saving the plaintext video;

[0048] Step 104, when downloading videos on a Class C device, the secure download mode is turned on, a security chip needs to be connected, and the user is prompted to enter the SN and PIN of the security chip;

[0049] Step 105, determine whether the connection to the security chip is successful, if successful, proceed to step 107, otherwise proceed to step 106;

[0050] Step 106, the download fails, prompting that the entered SN or PIN is incorrect and the security chip cannot be connected;

[0051] Step 107, after successfully connecting to the security chip, send a video download request to the GB35114 monitoring platform to download the video;

[0052] Step 108, obtain the ciphertext video key encryption key, namely e(vkek) and its version number vkek_version, from the SIP 200 message replied by the monitoring platform;

[0053] Step 109, since vkek will be updated regularly, when downloading the video of this segment, there may be multiple e(vkek) and vkek_verison written into the queue vque, which is convenient for subsequent decryption;

[0054] Step 110, GB35114 stipulates that the security parameter set of the video will not be encrypted, and the security parameter set stores the ciphertext video key, namely e(vek), and vkek_version;

[0055] Step 111, obtain the currently used e(vkek) in the queue vque through the vkek_version obtained from the security parameter set;

[0056] Step 112, whether e(vkek) is found, if yes, proceed to step 114, otherwise proceed to step 113;

[0057] Step 113, the download fails, and it is prompted that no valid e(vkek) is found;

[0058] Step 114, obtain the user's private key from the security chip, and decrypt e(vkek) into plain text vkek using the SM2 algorithm;

[0059] Step 115, use vkek to decrypt e(vek) into plaintext vek through the ECB mode of the SM4 algorithm;

[0060] Step 116, using the video key vek to decrypt the code stream through the OFB mode of the SM4 algorithm;

[0061] Step 117, check whether there is an SN.lic file in the security chip, where SN is the unique identifier of the security chip. If there is, proceed to step 119, otherwise proceed to step 118;

[0062] Step 118, create a text file SN.lic;

[0063] Step 119, opening the file SN.lic in append mode;

[0064] Step 120, generating a 16-byte unique identifier UUID and a new VKEK for the video file to be downloaded, denoted by newVKEK;

[0065] Step 121, the user inputs the play count playNum, the play start time playBegin, and the play end time playEnd of the video file;

[0066] Step 122, write UUID+newVKEK+playNum+playBegin+playEnd into the SN.lic file;

[0067] Step 123, generating a new video key newVEK in units of GOP (Group of picture), that is, the video key in each key frame interval is different, and encrypting newVEK into ciphertext e(newVEK) using newVKEK;

[0068] Step 124, write the encrypted e(newVEK) into the security parameter set of the current GOP and save it together with the video file;

[0069] Step 125, when saving the video file, first write the video file header, 4 bytes of "SVAC" and 16 bytes of UUID;

[0070] Step 126, continue to receive the code stream, re-encrypt the code stream with newVEK, and save the video file.

[0071] The security parameter set mentioned in the embodiment is one of the multiple NAL unit types in the SVAC video coding format and does not participate in encryption.

[0072] Embodiment three:

[0073] See also Figure 2 This embodiment provides a process for secure video playback based on the GB35114 protocol, and the specific steps are as follows.

[0074] The steps include:

[0075] Step 201, the client opens the video file and reads the file header;

[0076] Step 202, determine whether the file header is "SVAC", if yes, proceed to step 204, otherwise proceed to step 203;

[0077] Step 203, the file is not a securely downloaded video file, and the SVAC decoder is directly called to play it normally;

[0078] Step 204 indicates that the file is an encrypted file downloaded through security, and the user needs to be prompted to enter the SN and PIN of the security chip;

[0079] Step 205, whether the connection to the security chip is successful, if yes, proceed to step 207, otherwise proceed to step 206;

[0080] Step 206, the playback fails, and a prompt is displayed indicating that the connection to the security chip cannot be established;

[0081] Step 207, obtaining a 16-byte unique identifier UUID from the video file header;

[0082] Step 208, open the SN.lic file in the security chip;

[0083] Step 209, whether the file is opened successfully, if successful, proceed to step 211, if not, proceed to step 210;

[0084] Step 210: Playback fails, and a message indicates that there is no permission to play the video file.

[0085] Step 211, searching the playback information of the video file in the SN.lic file using the UUID obtained in step 207;

[0086] Step 212, read the play information play number playNum, video key encryption key newVKEK, play start time playBegin, play end time playEnd;

[0087] Step 213, determine whether playNum is greater than 0, if it is greater than 0, go to step 215, if not, go to step 214;

[0088] Step 214, the playback fails, and the playback count is 0;

[0089] Step 215, read the NAL unit in the video file;

[0090] Step 216, determining whether the NAL unit is a security parameter set, if yes, proceeding to step 217, otherwise proceeding to step 218;

[0091] Step 217 , obtain the ciphertext e(newVEK) of the video key from the security parameter set, and proceed to step 219 .

[0092] Step 218, determine whether newVEK already exists, if so, go to step 219, otherwise go to step 215.

[0093] Step 219, using the newVKEK obtained in step 212, and using the SM4 algorithm to decrypt the ciphertext e(newVEK) into the plaintext key newVEK.

[0094] Step 220, using the key newVEK, decrypt the ciphertext NAL unit into ciphertext through the SM4 algorithm.

[0095] Step 221, call the SVAC decoder to decode and play.

[0096] Step 222, update the play count of the current video file in SN.lic to playNum-1.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A video security download method based on GB35114 protocol, characterized in that: The method comprises: Initiate a video download request to the video surveillance platform with GB35114 function through the client, and after the request is successful, receive the encrypted SVAC video stream, and decrypt the encrypted SVAC video stream into a plaintext SVAC video stream; Get the file SN.lic named with the serial number of the security chip from the client security chip, generate a unique identifier UUID for the video file to be downloaded, and a new video key encryption key, represented by newVKEK; The playback information input by the user is received through the client, and the UUID, newVKEK and the playback information are written into the SN.lic file. For the received video bitstream, a new video key newVEK is generated in units of picture group GOP, and the bitstream is re-encrypted by newVEK so that the video key in each key frame interval is different. At the same time, newVEK is encrypted into ciphertext e(newVEK) by newVKEK, and the encrypted e(newVEK) is written into the security parameter set of the current picture group GOP, and the security parameter set is written together with the UUID to the downloaded video file and saved.

2. The video security download method based on GB35114 protocol according to claim 1 is characterized in that: Decrypting the encrypted SVAC video stream into a plaintext SVAC video stream specifically includes: After the request is successful, the ciphertext video key encryption key E (VKEK) is obtained from the response message of the monitoring platform, the security parameter set in the encrypted SVAC video stream is parsed, the ciphertext video key E (VEK) is obtained, the private key information of SM2 is read from the security chip, and E (VKEK) is decrypted into plaintext VKEK through the SM2 algorithm. The plaintext VKEK is used to decrypt E (VEK) based on the ECB mode of the SM4 algorithm to obtain the plaintext VEK. Finally, the plaintext VEK is used to decrypt the encrypted SVAC video stream based on the OFB mode of the SM4 algorithm to obtain the plaintext SVAC video stream.

3. A video security download and playback method based on GB35114 protocol, characterized in that: The method comprises: Safe video download: Initiate a video download request to the video surveillance platform with GB35114 function through the client, and after the request is successful, receive the encrypted SVAC video stream, and decrypt the encrypted SVAC video stream into a plaintext SVAC video stream; Get the file SN.lic named with the serial number of the security chip from the client security chip, generate a unique identifier UUID for the video file to be downloaded, and a new video key encryption key, represented by newVKEK; Receive the playback information input by the user through the client, write the UUID, newVKEK and the playback information into the SN.lic file, generate a new video key newVEK for the received video code stream in units of picture groups GOP, re-encrypt the code stream by newVEK so that the video key in each key frame interval is different, and encrypt newVEK into ciphertext e(newVEK) by newVKEK, write the encrypted e(newVEK) into the security parameter set of the current picture group GOP, and save the security parameter set and the UUID together with the downloaded video file; Video Safe Playback: When the client plays a securely downloaded video file, it first reads the SN.lic file in the security chip, then obtains the UUID and security parameter set from the video file, obtains e(newVEK) from the security parameter set, obtains the playback information corresponding to the video file in the SN.lic file through the UUID, and determines whether there is playback permission based on the playback information. If there is playback permission, the video code stream corresponding to the video file is decrypted through e(newVEK), and the SVAC decoder is called to decode and play.

4. The video security downloading and playing method based on GB35114 protocol according to claim 3 is characterized in that: The method also includes: determining whether the client is a GB35114 C-class device, and if so, performing video security downloading, and when downloading videos on the GB35114 C-class device, prompting the user to enter the SN and PIN of the security chip to connect the security chip, and after successfully connecting the security chip, initiating a video download request to a video monitoring platform with GB35114 function; otherwise, performing a normal download process, directly requesting video downloading from the video monitoring platform, downloading the plaintext video and saving it.

5. The video security downloading and playing method based on GB35114 protocol according to claim 3 is characterized in that: The method comprises: detecting whether there is an SN.lic file in the security chip, and if not, creating a file SN.lic in the security chip with the serial number of the security chip as the name.

6. The video security downloading and playing method based on GB35114 protocol according to claim 3 is characterized in that: Decrypting the encrypted SVAC video stream into a plaintext SVAC video stream specifically includes: After the request is successful, the ciphertext video key encryption key E (VKEK) is obtained from the response message of the monitoring platform, the security parameter set in the encrypted SVAC video stream is parsed, the ciphertext video key E (VEK) is obtained, the private key information of SM2 is read from the security chip, and E (VKEK) is decrypted into plaintext VKEK through the SM2 algorithm. The plaintext VKEK is used to decrypt E (VEK) based on the ECB mode of the SM4 algorithm to obtain the plaintext VEK. Finally, the plaintext VEK is used to decrypt the encrypted SVAC video stream based on the OFB mode of the SM4 algorithm to obtain the plaintext SVAC video stream.

7. The video security downloading and playing method based on GB35114 protocol according to claim 3 is characterized in that: The play information includes the play number playNum, the play start time playBegin and the play end time playEnd; Obtaining the playback information corresponding to the video file in the SN.lic file through the UUID, and determining whether there is playback permission based on the playback information includes: searching the corresponding UUID in the SN.lic file by obtaining the UUID from the video file, finding the UUID in the SN.lic file, obtaining the corresponding playback information, and obtaining the number of playbacks playNum, the playback start time playBegin, and the playback end time playEnd allowed for the video file. If playNum is greater than 0 and the playback time is between the start time playBegin and the playback end time playEnd, it is determined that there is playback permission, otherwise it is determined that there is no playback permission.

8. The video security downloading and playing method based on GB35114 protocol according to claim 7 is characterized in that: The method further includes: after the video file is played, updating the play count playNum of the current video file in SN.lic to playNum-1.

9. The video security downloading and playing method based on GB35114 protocol according to claim 3 is characterized in that: Decrypting the video code stream corresponding to the video file through e(newVEK) specifically includes: searching the corresponding newVKEK from SN.lic based on UUID, decrypting e(newVEK) into newVEK through SM4 algorithm based on newVKEK, and decrypting the video code stream of each frame in the video file through newVEK.

10. The video security downloading and playing method based on GB35114 protocol according to claim 3 is characterized in that: The method further comprises: when saving the securely downloaded video file, writing a video file header, wherein the video file header comprises characters "SVAC" and a UUID; When playing a securely downloaded video file, the client determines whether the file header of the video file contains the characters "SVAC". If the video file contains the characters "SVAC", the video file is determined to be an encrypted file downloaded securely, and the user is prompted to enter the SN and PIN of the security chip to connect the security chip. After the security chip is connected, the video security playback process is performed; otherwise, the video file is determined to be a non-securely downloaded video file, and the SVAC decoder is directly called for normal playback.

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